Selective one and two-stage trigger mechanism for firearms



y 8, 1965 w. L. GANDY 3,183,616

SELECTIVE ONE AND TWO-STAGE TRIGGER MECHANISM FOR FIREARMS Filed Oct. 6, 1964 4 Sheets-Sheet 1 A'rroaiq EY y 13, 1965 w. GANDY 3,183,616

SELECTIVE ONE AND TWO-STAGE TRIGGER MECHANISM FOR FIREARMS Filed Oct. 6, 1964 4 Sheets-5heet 2 :E'i5' 5 I8 16 iii INVENTOR WuTTEnLEm ATTORNEY y 8, 1965 w. L. GANDY 3,183,616

SELECTIVE ONE AND TWO-STAGE TRIGGER MECHANISM FOR FIREARMS Filed Oct; 6, 1964 4 Sheets-Sheet 3 INVENTOR Wurr EIl LEugiV ATTCSRNEY May 18, 1965 w. L. GANDY SELECTIVE ONE AND TWO-STAGE TRIGGER MECHANISM FOR FIREARMS 4 Sheets-Sheet 4 Filed Oct. 6, 1964 INVENTOR Warren L- Euniv United States Patent SELECTIVE ONE AND TWO-STAGE TRIGGER MECHANISM FOR FREAPMS Warren L. Gandy, St. Petersburg, Fla, assignor to the United States of America as represented by the Secretary of the Army Filed Oct. 6, 1964, Ser. No. 402,049

8 Claims. (Cl. 42-69) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to trigger mechanisms for firearms with reciprocal bolts which carry a spring-biased firing pin and relates more particularly to such trigger mechanisms which are especially adapted for marksmanship use.

It is the principal object of this invention to provide a trigger mechanism having a one-stage operation in which the firing pin sear is directly controlled by the trigger and a two-stage operation in which means are provided for finely adjusting the pressure required to actuate the trigger and the amount of displacement thereof required for release of the firing pin, with the trigger arranged to act as a safety for preventing accidental discharge of the firearm due to the fine adjustment operation.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a fragmentary, longitudinally cross-sectioned view of a firearm showing the trigger mechanism set for one-stage operation with the bolt releasably held by the primary sear which is under the direct control of the trigger;

FIG. 2 is a view similar to FIG. 1 but showing the trigger pulled to the firing position and the firing pin released from the primary sear;

FIG. 3 is a view similar to FIGS. 12 but showing the trigger mechanism set for two-stage operation with the sear lever engaged by the secondary sear;

FIG. 4 is a view similar to FIG. 3 but showing the trigger pulled to the end of its slack movement and the upper arm thereof displaced free of the primary sear;

FIG. 5 is a view similar to FIG. 4 but showing the bolt released through displacement of the secondary sear by the trigger;

FIG. 6 is a view taken along line 66 of FIG. 1; and

FIG. 7 is a perspective, exploded View of the trigger mechanism.

Shown in the figures is a rifle 12 having a receiver 14 in which a bolt 16 is disposed for reciprocation between a battery and a recoil position. Bolt 16 carries a firing pin 18 which is biased by a spring 20 from a cocked to a striking position and which is provided at the rear end with a depending tang 22 that extends below the bottom of the bolt.

A trigger mechanism 24 is mounted in receiver 14 below the path of movement of bolt 16 and so as to engageably cooperate with tang 22 as hereinafter described. Trigger mechanism 24 includes a housing 26 in which a primary sear 28 is mounted for pivotal displacement between an upper searing position and a lower release position on a pin 30 that extends laterally through the rear end of the primary sear and the top rear corner of the housing.

Primary sear 28 is provided with a top surface 32 which is slidingly engageable by the bottom end of tang 3,l83,fil6 Patented May 18, 1%65 22 during travel of the bolt 16 to recoil position for depressing the primary sear to its release position and permit displacement of the tang thereby. The top rear corner of primary sear 23 is cut away at 34 to form a latching surface 36 which is contactable by tang 22, when bolt 16 moves forwardly from recoil position and the primary sear is in the searing position, to cock firing pin 13 and hold it in its cocked position after bolt 16 reaches battery position. Tang 22 is released from latching surface 36 when primary sear 28 is pivoted to its release position. Primary sear 28 is biased to its searing position by a spring 38 which is overcome by the tension of firing pin spring 20 when the primary sear is free for pivotal displacement to its release position.

The bottom front section of primary sear 28 is relieved at 4%? to form a rear latching lip 42 at the substantially right angular junction of rear side 44 of the relief with bottom side 43 of the primary sear. Relief 40 also forms a forwardly extending arm 48 having a front latching lip 50 at the front end thereof. Rear latching lip d2 cooperates with a trigger 52 pivotally mounted in housing 26, as hereinafter described, for releasably blocking primary sear 28 in its searing position against the bias of firing pin spring 20.

Trigger 52 is mounted on a pin 54- for pivotal displacement between a forward normal position and a rearward firing position and consists of a single lever comprising a fingerpiece 56 which extends downwardly from housing 26 through an opening 57 in bottom side 59 thereof and an arcuately formed arm 58 which extends upwardly and rearwardly from the fingerpiece above the pin. A stop-arm 60 extends rcarwardly from the junction of arm 58 and fingerpiece 56.

Provided in the free end of arm 58 is a notch 62 which releasably engages rear latching lip 42 when trigger 52 is in its normal position and primary sear 28 is in its searing position to block pivotal displacement of the primary sear. When trigger 52 is pulled to the firing position, notch 62 is disengaged from rear latching lip 42 thus freeing primary sear 28 for displacement by firing pin spring 20, through tang 22, to the release position, whereby firing pin 18 is released for displacement to its striking position. Trigger 52 is biased to its normal position by a spring 64 and such normal position, which is also the engaging position of arm 58, is adjustably established by a screw 66 which is threadingly mounted in housing 26 for terminal contact with the underside of stop-arm 6t). Adjustment of screw 66 determines the amount of displacement required of trigger 52 for release of primary sear 28.

When trigger mechanism 24 is set for two-stage operation, primary sear 28 is releasably blocked by a sear lever 68 which is mounted for pivotal displacement between an engaging position and a release position by a pin 70 which extends laterally through housing 26 and the top end of the sear lever. An upwardly facing ledge 72 is formed on the rear side of sear lever 68 below pin 76 so as to be contactable with front latching lip 59 when the sear lever is in its engaging position to block displacement of primary sear 23 from its searing position and so that the bias of firing pin spring 20, transferred through the primary sear, is converted to pivotal displacement of the :sear lever to the release position. When sear lever 68 is pivoted to its engaging position, the contact of ledge 72 with front latching lip 50 raises the rear latching lip 42 slightly above the position in which it is held by trigger 52 so that the rear latching lip is disengaged from notch 62.

Sear lever 6% is pivoted manually to its engaging position by a cocking trigger 74 which is pivotally mounted on a transverse pin '76 through housing 26 and which includes a manual lever 78 that extends downwardly from the housing forwardly of fingerpiece 56 and an arcuately faced contact portion 79 which extends upwardly from the manual'lever in front of scar lever 68. Thus, when manual lever 78 is pushed forwardly, contact portion 79 is pressed rearwardly against the front face of sear lever 68 for actuation thereof to the engaging position. Sear lever 68 is biased to its release position by a spring 80 and another spring 82 returns cocking trigger 74 to its normal position after manual pressure is released therefrom.

Sear lever 68 is releasably held in its engaging position by a secondary sear 84 which is essentially of inverted T-configuration; Extending vertically through secondary sear 84 is a channel 86 which is arranged to receive trigger 52 and which bifurcates the vertical leg of the secondary sear to form a pair of laterally spaced hangers 88. Mating holes in hangers 88 receive pin 54 to provide pivotal support for secondary sear 84. Channel 86 has suflicient longitudinal length to permit relative displacement of trigger 52 and secondary sear 84. The free rearward displacement of trigger 52, relative to secondary sear 84, is adjustably limited by a screw 90 longitudinally mountedthrough a lug 92 which depends from a rear arm 93 of secondary sear 84. Rear arm 93 extends rearwardly of channel 86 beneath bottom side 59.

Secondary sear 84 also includes a front arm 94 which is partially received by opening 57 and which is terminated by a flange 96 that extends forwardly of the opening below bottom side 59. The rearward displacement of secondary sear 84 is adjustably limited by a screw 98 threadingly mounted through rear arm 93 for terminal contact with bottom side 59. A lip 100' with a rear side 102 extends upwardly from front arm 94 and such rear side is contactable by sear lever 68 when primary sear 28 is displaced thereby to its searing position to releasably hold the sear lever in its engaging position. The degree of displacement required of secondary sear 84 for release of sear lever 68 is adjustably controlled by a spacer-plate 104, essentially of S-configuration, which is mounted on the top of front arm 94, between lip 100 and hangers 88, by a screw 108. The top-forward section of spacer-plate 104 forms a platform 110 which extends forwardly to terminate near rear side 102 of lip 100 and thereby form a latching surface 112 on such rear side between platform 110 and the top of lip 100. Platform 110 is bent resiliently downward and is adjustably elevated by a screw 114 which is mounted vertically through front arm 94 so as to terminally contact the underside of platform 110 for adjusting the height of latching surface 112 and, therefore, the degree of displacement required of secondary sear 84 for release of sear lever 68.

- presses downward'on the top of block 118 with sufl'icient force to displace the block for increasing the force applied by spring 122 to secondary sear 84. The force applied by spring 122 to secondary sear 84 is adjustable by a screw126 which is mounted through housing 26 to act against the bottom side of block 118 for changing/the pivotalpositionthereof. Springs 122 and 124 aredesigned so't hat secondary sear 84 is displaceable'to its release position by a pressure of one to three ounces applied against trigger 52.

Operation 1 When rifle'1i2 is ready to be fired," as shown in FIG. 1',

bolt 16 is in battery position and firing pin 18 is held cocked bythe engagement of tang 22 thereon with latching surface 36 of primary sear 28 which is held in its searing position against the bias of firing pin spring 20 by the blocking engagement of rear latching lip 42 with notch 62 in trigger 52. Also, sear lever 68 is pivoted forwardly to its release position so that ledge 72 thereon is free of contact by front latching lip 50 when primary sear 28 is freed for pivotal displacement to its release position.

In this state, trigger mechanism 24.functions as a single lever, one-stage mechanism so that, when trigger 52 is pulled to the firing position, arm 58 is displaced forwardly to disengage itself from primary sear 28. Primary sear 28 is thus free to pivot downwardly under the influence of firing pin spring 20, allowing firing pin 18 to be propelled forwardly thereby to its striking position. Screw 66 adjusts the amount of movement of trigger 52 necessary to disengage notch 62 from rear latching lip 42.

Trigger mechanism 24 may also function as a two-stage unit by'pushing forwardly'on cocking trigger 74, when bolt 16 is in battery position, whereby sear lever 68 is pivoted rearwardly into searing engagement with secondary sear 84. At the same time, the contact of ledge 72 with front latching lip 50 lifts primary sear 28 out of engagement with trigger 52 so that release of firing pin 18 by primary sear 28 is now controlled by sear lever 68 which, in turn, is controlled by secondary sear 84. Notch 62, however, remains positioned to re-engage primary sear 28 if accidentally released by secondary sear 84 before trigger 52 is pulled and thereby the trigger acts as a safety against accidental discharge of firearm 12.

The pressure necessary to actuate trigger 52, when trigger mechanism 24 is set for two-stage operation, may be varied between one and three ounces by adjusting the position of block 118- which controls the tension of spring 122 against secondary sear 84.

7 When trigger mechanism 24 is set for two-stage operation, the initial movement of trigger 52, when pulled, consists of free or slack movement of fingerpiece 56 to the rear. This causes arm 58 to move forwardly from its blocking. position under primary sear 28 and thereby trigger 52 no longer performs a safety function. The slack movement of trigger 52 is ended when fingerpiece 56 contacts screw 90. Further rearward movement of fingerpiece 56 causes secondary sear 84 to pivot to its release position, thereby releasing sear lever 68 which is, consequently, free to be swung forwardly by the bias of firing pin spring 20 until primary sear 28 is unblocked. When primary sear 28 is released, primary sear 28 is free to be pivoted by firing pin spring 20 until firing pin 18 is released for forward displacement to its striking position. By adjustment of screw 90, objectionable overtravel of trigger 52 after release of firing pin 18 can be eliminated.

By adjustment of the tension of spring 122 against sec is provided herein a trigger mechanism which is especially well adapted for marksmanship use by including a onestage operation in which the firing pin sear is controlled directly bythe trigger and a two-stage operation which permits fine adjustment of the pressure and displacement requirements while being safe from accidental discharge.

Although a particular embodiment of the invention has been described in detail herein, it'is evident that many 7 V variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations. Q r

I claim:

i 1. In a firearm having a receiverwith a bolt dispo'sed therein for longitudinal reciprocation, a firing'pin' slidingly mounted in the bolt for displacement between a cocked and a striking position, a firing pin spring for biasing said firing pin to the striking position, and a trigger mechanism mounted in the receiver for engageable control of said firing pin, said trigger mechanism including a housing, a primary sear mounted for pivotal displacement between a searing position and a release position, cooperating means on said primary sear and said firing pin disposed for engagement when said primary sear is in the searing position for blocking displacement of said firing pin from the cocked position and for transferring the bias of said firing pin spring to said primary sear for displacement thereof to the release position, a trigger pivotal between a normal and a firing position, an integral arm on said trigger disposed for releasably blocking displacement of said primary sear to the release position when said trigger is in the normal position, means for adjusting the amount of displacement required of said trigger to release said primary sear, a trigger actuated secondary sear, and means for selectively transferring control of said primary sear from said arm to said secondary sear.

2. The firearm as defined in claim I and including means providing for free displacement of said trigger respective to said secondary sear during initial displacement of said trigger from the normal position, and adjustable means for transferring displacement of said trigger from the normal position to said secondary sear when said arm is free of said primary sear, whereby said trigger functions as a safety to prevent accidental discharge of the firearm when control of said primary sear is transarm to said secondary sear.

3. The firearm as defined in claim 1 wherein said trigger and said secondary sear are mounted on a common pin for relative pivotal displacement including free movement of said trigger relative to said secondary sear during initial displacement of said trigger from the normal position, and including a screw mounted on said secondary sear for terminal contact with said trigger for adjustably limiting the free movement thereof relative to said secondary sear to a point where said arm is free of blocking interference wtih said primary sear when said trigger makes contact with said screw and for transferring further displacement of said trigger to the firing position to said secondary sear for actuation thereof.

4. The firearm as defined in claim 1 wherein said means for transferring control of said primary sear from said arm to said secondary sear includes a pivotal cocking trigger, a scar lever mounted at the upper end thereof for pivotal displacement by said cocking trigger from a release to an engaging position, a ledge on said sear lever engageable with said primary sear when said sear lever is actuated to the engaging position for releasing said primary sear from blocking relationship with said arm and for releasably blocking said primary sear from displacement from the searing position when said sear lever is in the engaging position, and means on said secondary sear for releasably holding said sear lever in the engaging position.

5. The firearm as defined in claim 4 and including means for actuating said secondary sear from a searing to a release position by said trigger, and means mounted on said secondary sear for cooperation with said sear lever for adjusting the amount of displacement required of said secondary sear from the searing position for release of said sear lever.

6. The firearm as defined in claim 5 wherein said ledge is positioned relative to the pivotal point of said sear lever so that the bias of said firing pin spring is transferred through said primary sear to said sear lever for displacement thereof to the release position.

7. The firearm as defined in claim 5 wherein said secondary sear is provided with a lip, and a rear side of said lip contactable by the free end of said sear lever for blocking displacement thereof from the engaging position when said secondary sear is in the searing position, and including a spacer plate mounted on said secondary sear, a platform formed at the front end of said spacer plate so as to be contactable by the free end of said sear lever and so as to terminate adjacent said rear side, and means for adjusting the height of said platform to control the depth of said rear side contactable by said sear lever.

8. The firearm as defined in claim 5 and including a spring device for adjustably controlling the amount of pressure to be applied to said trigger for actuating said secondary sear to the release position, said spring device including an elongated block pivotally mounted in said housing rearwardly of said trigger, a spring of hairpin configuration mounted at the ends to said block so as to extend therefrom and press against said secondary sear for displacement thereof to the searing position, another spring having a tension greater than said hairpin spring mounted on said housing for contact by said block for displacement thereof to increase the tension applied by said hairpin spring to said secondary sear, and a screw adjustably mounted in said housing for terminal contact with said block to oppose the tension of said another spring for adjustably positioning said block and the tension applied to said secondary sear by said hairpin spring.

No references cited.

BENJAMIN A. BORCHELT, Primary Examiner. 

1. IN A FIREARM HAVING A RECEIVER WITH A BOLT DISPOSED THEREIN FOR LONGITUDINAL RECIPROCATION, A FIRING PIN SLIDINGLY MOUNTED IN THE BOLT FOR DISPLACEMENT BETWEEN A COCKED AND A STRIKING POSITION, A FIRING PIN SPRING FOR BIASING SAID FIRING PIN TO THE STRIKING POSITION, AND A TRIGGER MECHANISM MOUNTED IN THE RECEIVER FOR ENGAGEABLE CONTROL OF SAID FIRING PIN, SAID TRIGGER MECHANISM INCLUDING A HOUSING, A PRIMARY SEAR MOUNTED FOR PIVOTAL DISPLACEMTN BETWEEN SEARING POSITION AND A RELEASE POSITION, COOPERATING MEANS ON SAID PRIMARY SEAR AND SAID FIRING PIN DISPOSED FOR E NGAGEMENT WITH SAID PRIMARY SEAR IS IN THE SEARING POSITION FOR BLOCKING DISPLACEMENT OF SAID FIRING PIN FROM THE COCKED POSITION AND FOR TRANSFERRING THE BIAS OF SAID FIRING PIN SPRING TO SAID PRIMARY SEAR FOR DISPLACEMENT THEREOF TO THE RELEASE POSITION, A TRIGGER PIVOTAL BETWEEN A NORMAL AND A FIRING POSITION, AN INTEGRAL ARM SAID TRIGGER DISPOSED FOR RELEASABLY BLOCKING DISPLACEMENT OF SAID PRIMARY SEAR TO THE RELEASE POSITION WHEN SAID TRIGGER IS IN THE NORMAL POSITION, MEANS FOR ADJUSTING THE AMOUNT OIF DISPLACEMENT REQUIRED OF SAID TRIGGER TO RELEASE SAID PRIMARY SEAR, A TRIGGER ACTUATED SECONDARY SEAR, AND MEANS FOR SELECTIVELY TRANSFERRING CONTROL OF SAID PAIMARY SEAR FROM SAID ARM TO SAID SECONDARY SEAR. 